Study on protection role of BCG Vaccine in Immunization against Enteropathogenic Escherichia coli and there challenge Infection and Pathology in white albino mice

This study aimed to determine the role of BCG in immunization of white mice against EnteropathogenicEscherichia coli (EPEC) and there role against challenge infection and pathology with this microbial agent . EPEC was isolated from diarrhea ofchildren , routinely diagnosed and serotyping were identified as 0119 EPEC . Then three groups of mice (30 each group) were taken , first group immunized with whole killed EPEC Ag, the second group were immunized with whole killed EPEC AgandBCG Vaccine , the immunization were occurred at two doses 14 days intervals , third group were injected with phosphate buffer saline ( pbs- control group).Results revealed at 28th days post immunization , increase in DTH- skin test thickness at 24, 48 hrs in group immunized with whole killed EPEC Ag and BCG ( group2 ) comparable to group 1 ( immunized with whole killed cell Ag alone and group 3 ( control group) . Also humeral immune (HI) response elevated in group 2 comparable to group 1 and control group3 . The HI response accompanied by elevation of IgG and IgM level in group 2 comparable to group 1 and control group 3 . On another hand bacterial isolation were mild in group 2 and moderate in group 1 compable to control group 3 following challenge dose infection with EPEC. Also more localized granulomatous lesion were seen in internal organs specially at 14th. , 21th days post inoculation of challenge dose in group 2 comparable to group 1 and no lesion in control group 3.
Conclusion :
1- Immunization group 2 of white mice with whole killed EPEC Ag and BCG vaccine give high level of CMI and HI with elevation of IgG, IgM comparable to group 1 immunized with whole killed EPEC Ag alone .
2- Mild bacterial isolates seen in internal organs of immunized group 2 with whole killed EPEC Ag and BCG vaccine comparable to moderate bacterial isolates in whole killed EPEC Ag alone group 1 .
3- More localized granulomas in internal organs of immunized group 2 with whole killed EPEC and BCG vaccinecomparable to mild granulomas in immunized whole killed EPEC Ag alone group 1.